1. Field of the Invention
The present invention relates to a toner as a developing agent, and a toner cartridge, a development device and an image forming apparatus containing the toner.
2. Description of the Related Art
In order to improve the quality of a print image (toner image) formed on a sheet by an image forming apparatus employing an electrophotographic process, there has been a proposal specifying melt viscosity and a ratio of a toner to be used. See Japanese Patent Application Publication No. 2015-68889 (in particular, claims 1 to 3), for example.
However, it is sometimes impossible to maintain the quality of print images at a high level just by specifying the melt viscosity and the ratio of the toner. For example, even when the color tone of a print image just after the printing is excellent, colors of the print image can fade away due to chronological change (i.e., light resistance is insufficient). Further, when the printing is performed in consideration of the chronological change in the color tone of the print image, there are cases where the color tone of the print image just after the printing is inappropriate. Incidentally, the color tone means a detailed tone of color, such as subtle gradation of color, subtle deviation in color, and so forth.